What is ‘soil-forming material’?
This term has been employed to describe non soil materials used in land reclamation to support vegetation growth. These are usually derived from mineral wastes, such as:
- Overburden materials
- Uneconomic geological materials encountered during quarrying or mining
- From the treatment or refinement of mineral ores or raw products.
In addition, other industrial by-products such as pulverised fuel ash (pfa) and gypsum from thermal power stations are sometimes used for this purpose; as are construction residues.
Soil-forming materials must also have the propensity to turn into soils over time, and this process is usually encouraged by treatment to relieve compaction, the incorporation of organic matter such as greenwaste compost, and the choice of appropriate vegetation types that will endure and improve the quality of the substrate.
The majority of Forest Research’s experience of growing trees and other forms of vegetation on reclaimed land has been using soil-forming materials rather than true soil. So significant and successful research campaigns have been achieved on:
- Opencast coal and colliery spoil
- China clay spoil
- Sand and gravel wastes
- Brick clays
- Fines and overburdens from construction sites.
'Soil-forming materials: their use in land reclamation' for the Department of the Environment, Transport and the Regions in 1999 (published by the Stationery Office).